code: def get_only_parent(self):  # type: () -> Node
      if len(self.parents) != 1:
          raise ValueError(
              "Node ({}) expected to have 1 parent. Found {}.".format(
                  self, len(self.parents)
              )
          )
      return self.parents[0]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  from onnx import numpy_helper, ValueInfoProto, AttributeProto, GraphProto, NodeProto, TensorProto, TensorShapeProto
  from typing import Any, Text, Iterable, List, Dict, Sequence, Optional, Tuple, Union
  from typing_extensions import Protocol
  import numpy
label_desc: Use image node_id 4 for calling the Node obj's underlying member method code with example usage: obj.get_only_parent() and returns: self